Thermoset polyurethane elastomers and polyurea elastomers made using high functionality, low unsaturation level polyols prepared with double metal cyanide catalysts

ABSTRACT

This invention relates to a method of fabricating a thermoset elastomer which comprises the steps of: (a) fabricating a polyol having a molecular weight of between about 400 and about 15,000 and having a level of end group unsaturation of not greater than 0.04 milliequivalents per gram of polyol, said polyol being fabricated in the presence of a double metal cyanide catalyst, (b) reacting said polyol with a polyisocynate to produce an isocyanate-terminated prepolymer, and (e) reacting said isocyanate-terminated prepolymer with a chain extender other than ethylene glycol in a mold in order to produce the elastomer. Also claimed is the elastomer produced by the above method utilizing a one-shot technique.

FIELD OF THE INVENTION

The present invention relates generally to the production ofpolyurethane and polyurea elastomers and, more specifically, to theproduction of polyurethane and polyurea elastomers utilizing highfunctionality, low unsaturation level polyols prepared by double metalcyanide complex catalysis.

BACKGROUND OF THE INVENTION

The use of double metal cyanide catalysts in the preparation of highmolecular weight polyols is well-established in the art. For example,U.S. Pat. No. 3,829,505, assigned to General Tire & Rubber Company,discloses the preparation of high molecular weight diols, triols etc.,using these catalysts. The polyols prepared using these catalysts can befabricated to have a higher molecular weight and a lower amount of endgroup unsaturation than can be prepared using commonly-used KOHcatalysts. The '505 patent discloses that these high molecular weightpolyol products are useful in the preparation of nonionic surface activeagents, lubricants and coolants, textile sizes, packaging films, as wellas in the preparation of solid or flexible polyurethanes by reactionwith polyisocyanates.

Certain thermoset polyurethane elastomers produced using triols made byDMC catalysis are also known. More specifically, U.S. Pat. No. 4,242,490discloses the preparation of such elastomers by reacting a DMCcatalyst-prepared polypropylene ether triol having a molecular weight offrom 7,000 to 14,000, ethylene glycol, and toluene diisocyanate in aspecified range of molar ratios using either a prepolymer process or a"one-shot" process.

Heretofore, the use of high molecular weight polyols made with doublemetal cyanide catalysts in combination with chain exterders other thanethylene glycol in the preparation of thermoset elastomers, particularlythermoset elastomers characterized by a combination of high tensilestrength, good elongation, and high tear strength, has not been knownbased upon the knowledge of the present inventor. The discovery of suchelastomers would be highly desired by the elastomer manufacturingcommunity.

SUMMARY OF THE INVENTION

In one aspect, the present invention relates to a thermoset polyurethaneor polyurea elastomer made by reacting an isocyanate-terminatedprepolymer with a chain-extender other than ethylene glycol, theisocyanate-terminated prepolymer being the reaction product of apolyisocyanate and a polyether polyol prepared utilizing a double metalcyanide complex catalyst and having a molecular weight of between about400 and about 15,000 (advantageously between 1,000 and 6,000), saidpolyol having an end group unsaturation level of no greater than 0.04milliequivalents per gram of polyol, the equivalent ratio of NCO groupson said polyisocyanate to active hydrogen groups on said polyol pluschain extender being between about 1:0.7 and about 1:1.3, and the molarratio of chain extender to polyol being between about 0.15:1 and about1.3:1.

In another aspect, the present invention relates to a thermosetpolyurethane or polyurea elastomer made by reacting in a "one-shot"process a polyether polyol, a polyisocyanate, and a chain-extender otherthan ethylene glycol, the polyether polyol being prepared utilizing adouble metal cyanide complex catalyst and having a molecular weight ofbetween about 400 and about 15,000 (advantageously between 1,000 and6,000), said polyol having an end group unsaturation level of no greaterthan 0.04 milliequivalents per gram of polyol, the equivalent ratio ofNCO groups on said polyisocyanate to active hydrogen groups on saidpolyol plus chain extender being between about 1:0.7 and about 1:1.3,and the molar ratio of chain extender to polyol being between about0.15:1 and about 1.3:1.

In yet another aspect, the present invention relates to a method offabricating a cast elastomer which comprises the steps of:

(a) fabricating a polyol having a molecular weight of between about2,000 and about 15,000 and having a level of end group unsaturation ofno greater than 0.04 milliequivalents per gram of polyol, said polyolbeing fabricated in the presence of a double metal cyanide catalyst,

(b) reacting said polyol with a polyisocyanate to produce anisocyanate-terminated prepolymer, and

(c) reacting said isocyanate-terminated prepolymer with a chain extenderother than ethylene glycol in a mold in order to produce a castelastomer

In still another aspect, the present invention relates to an elastomeras describe above but wherein the chain extender is ethylene glycol andthe polyisocyanate is MDI.

These and other aspects will become apparent upon reading the followingdetailed description of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The polyurethane elastomers of the present invention may be made by theprepolymer process or the one-shot process. The polyurethaneisocyanate-terminated prepolymer that is utilized when employing theprepolymer process according to the invention is prepared by reacting anorganic polyisocyanate with a polyalkylene ether polyol(s) in anequivalent ratio of NCO to OH groups of from about 1.02/1 to about 15/1,using standard procedures, to Yield an isocyanate-terminated prepolymerof controlled molecular weight. Preferably, the NCO/OH ratio ranges fromabout 1.3/1 to about 5/1. The reaction may be accelerated by employing acatalyst; common urethane catalysts are well known in the art andinclude numerous organometallic compounds as well as amines, e.g.,tertiary amines and metal compounds such as lead octoates, mercuricsuccinates, stannous octoate or dibutyltin dilaurate may be used. Anycatalytic amount may be employed; illustratively, such amount varies,depending on the particular catalyst utilized, from about 0.01 to about1 percent by weight of the polyurethane prepolymer.

Preferred polyol reactants are the polyether diols and the polyethertriols, and combinations thereof. Suitable polyether triols includevarious polyoxyalkylene polyols and mixtures thereof. These can beprepared, according to well-known methods, by condensing an alkyleneoxide, or a mixture of alkylene oxides using random or step-wiseaddition, with a polyhydric initiator or mixture of initiators.Illustrative alkylene oxides include ethylene oxide, propylene oxide,butylene oxide, amylene oxide, aralkylene oxides such as styrene oxide,and the halogenated alkylene oxides such as trichlorobutylene oxide andso forth. The most preferred alkylene oxide is propylene oxide or amixture thereof with ethylene oxide using random or step-wiseoxyalkylation.

The polyhydric initiator used in preparing the polyether triol reactantincludes the following and mixtures thereof: the aliphatic triols suchas glycerol, propoxylated glycerol adducts, trimethylolpropane,triethylolpropane, trimethylolhexane, and the like.

A preferred group of polyhydric initiators for use in preparing thepolyether triol reactant is one which comprises triols such as glycerol,propoxylated glycerol adducts, trimethylolpropane and the like.

The polyether diols are prepared by an analogous reaction of alkyleneoxide, or mixture of alkylene oxides with a polyhydric initiator. Inthis case the initiator is a diol such as ethylene glycol, 1,3-propyleneglycol, dipropylene glycol, butylene glycols, butane diols, pentanediols, and the like.

A preferred group of polyhydric initiators for use in preparing thepolyether diol reactant is one which comprises diols such as ethyleneglycol, diethylene glycols, propylene glycol, dipropylene glycol, orwater.

The alkylene oxide-polyhydric initiator condensation reaction ispreferably carried out in the presence of a double metal cyanidecatalyst. Without wishing to be bound by any particular theory, it isspeculated by the present inventor that unsaturated end groups result inmonofunctional species that act as chain stoppers in elastomerformation. In polyol synthesis with KOH catalysis the unsaturationformed increases as a direct function of equivalent weight. Eventuallyconditions are established wherein further propylene oxide additionfails to increase the molecular weight. In other words the use of alkalicatalysts to produce high molecular weight, hydroxy terminatedpolyoxypropylene ethers results in a substantial loss in hydroxyfunctionality. With double metal cyanide catalysis much lessunsaturation is formed allowing higher equivalent weight polyols to beprepared.

The double metal cyanide complex class catalysts suitable for use andtheir preparation are described in U.S. Pat. Nos. 4,472,560 and4,477,589 to Shell Chemical Company and U.S. Pat. Nos. 3,941,849;4,242,490 and 4,335,188 to The General Tire & Rubber Company. Theteachings of the foregoing patents are incorporated herein by reference.

One double metal cyanide complex catalyst found particularly suitablefor use is a zinc hexacyanometallate of formula:

    Zn.sub.3 [M(CN).sub.6 ].sub.2.xZnCl.sub.2.yGLYME.zH.sub.2 O

wherein M may be Co(III), or Cr(III) or Fe(II) or Fe(III); x, y, and zmay be fractional numbers, integers, or zero and vary depending on theexact method of preparation of the complex.

Any suitable organic polyisocyanate, or mixture of polyisocyanates, maybe used in the elastomer-forming process of the present invention.Illustrative are toluene diisocyanate, such as the 80:20 and the 65:35mixtures of the 2,4- and 2,6-isomers, ethylene diisocyanate, propylenediisocyanate, methylene-bis (4-phenyl) isocyanate (also referred to asdiphenylmethane diisocyanate or MDI), xylene diisocyanate (XDI),isophorone diisocyanate (IPDI), 3,3'-bistoluene-4,4'-diisocyanate,hexamethylene diisocyanate (HDI), hydrogenated MDI, hydrogenated XDI,and modified liquid MDI adducts such as carbodiimide-modified MDI,naphthalene-1,5-diisocyanate, the polymeric isocyanates such aspolyphenylene polymethylene isocyanate (PMDI), mixtures and derivativesthereof, and the like. In accordance with a particularly preferredembodiment of the invention, there is employed an isomeric mixture of2,4- and 2,6-toluene diisocyanate in which the weight ratio of the2,4-isomer to the 2,6-isomer is from about 60:40 to about 90:10, andmore preferably from about 65:35 to about 80:20, as well as MDI.

Chain extenders useful in the present invention include diols anddiamines such as 4,4'-methylene bis(2-chloroaniline) ("MOCA"), butanediol, hexane diol, propylene glycol, bisphenol A, or polyalkylene oxidepolyols with molecular weights between 100-500. The chain extenders canalso be triols such as glycerine, trimethylol propane, or propoxylatedadducts of glycerine or trimethylol propane or amines likediethyltoluene diamine, ethylene diamine, substituted aromatic diaminessuch as the product commercially available as UNILINK 4200, a product ofUOP, Inc, triisopropyl amine, methylene bis(orthochloro-aniline),N,N-bis(2-hydroxypropyl)-aniline which is commercially available asISONOL 100, a product of Dow Chemical Corp., and the like, andcombinations thereof. Preferred chain extenders include MOCA, butanediol, trimethylol propane, diethyltoluene diamine,N,N-bis(2-hydroxypropyl)-aniline, and combinations thereof. The chainextension can be conducted either in situ during the prepolymerformation or in a separate reaction step.

In preparing the polyurethane and/or polyurea elastomer, the polyetherpolyol(s), polyisocyanate(s), chain extender(s), and other componentsare reacted, typically under conditions of an elevated temperature.Urethane forming catalysts can be used as well as antioxidants or otherantidegradants. The elastomer-forming components may be mixed with theusual compounding ingredients, e.g. plasticizers, adhesion promoters,fillers and pigments like clay, silica, fumed silica, carbon black,talc, phthalocyanine blue or green, TiO₂, U-V absorbers, MgCO₃, CaCO₃and the like. The compounding ingredients, such as fillers, are suitablyemployed in the elastomer in an amount of between 0 and about 75 weightpercent based upon the weight of the elastomer. The polymerizationreaction may be carried out in a single reaction (one-shot process), orin one or more sequential steps (prepolymer process). In the one-shotprocess, all the isocyanate-reactive components are reactedsimultaneously with the polyisocyanate. In such process, it is normalpractice to blend all components except the polyisocyanate into a"B-side" mixture, which is then reacted with the polyisocyanate to formthe polyurethane and/or polyurea elastomer. However, the order of mixingis not critical as long as the components do not undesirably reactbefore all components are present. The reaction mixture is usually thenplaced in a mold and cured at a suitable temperature. The apparatus usedfor blending and molding is not especially critical. Hand mixing,conventional machine mixing, and the so-called reaction injectionmolding (RIM) equipment are all suitable. In the prepolymer process, allor a portion of one or more of the isocyanate reactive materials isreacted with a stoichiometric excess of the polyisocyanate to form anisocyanate-terminated prepolymer. This prepolymer is then allowed toreact with the remaining isocyanate-reactive materials to prepare thepolyurethane and/or polyurea elastomer. The prepolymer can be preparedwith either the polyether or the chain extender, or a mixture of both.

As used herein, the term "molecular weight" is intended to designatenumber average molecular weight.

While the invention has been described above with reference to specificembodiments thereof, it is apparent that many changes, modifications andvariations can be made without departing from the inventive conceptdisclosed herein. Accordingly, it is intended to embrace all suchchanges, modifications and variations that fall within the spirit andbroad scope of the appended claims. All patent applications, patents andother publications cited herein are incorporated by reference in theirentirety.

EXAMPLE 1 Preparation of Cast Elastomers

A comparison was made between the performance of conventional POLY-G®polyols and the new POLY-L™ high molecular weight polyols containing lowunsaturation levels in cast elastomers.

The compositions of the polyols that were evaluated in cast elastomersare presented in Table 1. POLY-L polyols were prepared with double metalcyanide catalysts. Note the dramatic difference in the 6200 MW triol(83-26) prepared with KOH (0.095 meq/g unsat., 43 mole % monol, 2.12functionality) and the 6200 MW triol (X-383-26) prepared with DMCcatalyst (0.018 meq/g unsat., 10 mole % monol, 2.77 functionality). The10,000 molecular weight triols prepared with DMC catalyst (X-385-17 andX-330-18) also had low unsaturation levels and relatively highfunctionalities compared to the conventional 6200 MW polyol. Acomparison of the 4200 MW diols shows a similar dramatic difference. The4200 MW diol prepared with KOH catalyst (20-28) had an unsaturationvalue of 0.097 meq/g, 34 mole % monol, and a functionality of 1.66,while the 4200 MW diol prepared with DMC catalyst had an unsaturationvalue of 0.015 meq/g, 6 mole % monol and a functionality of 1.94. The10,000 molecular weight diol (X-220-10) had an unsaturation value of0.020 meq/g and a higher calculated functionality than the conventional4200 MW diol.

Prepolymer Preparation

The diisocyanate was added to a resin flask under nitrogen and heated to55C. Polyol was added through a dropping funnel over a period of about30 minutes. The temperature was raised to 80C and stirred until aconstant percent free NCO, as measured by dibutyl amine titration, wasobtained (typically 3 hours with MDI and 5 hours with TDI).

Cast Elastomer Preparation

The prepolymer was added to a resin flask, degassed under vacuum, andoptionally heated to 60C. The extender was added using a 103 index andthe mixture was stirred vigorously and degassed for two minutes. Themixture was poured between glass plates using a 1/8 spacer and cured inan oven at 110° C. for 16 hours.

The elastomers were tested using standard ASTM procedures: TensileStrength (psi) and Elongation (%) --ASTM D-412; Shore A hardness--ASTMD-2240; Die "C" Tear Strength--ASTM D-624.

                                      TABLE 1                                     __________________________________________________________________________    Polyol Composition POLY-G ® polyols were prepared with KOH catalyst       Poly-L ™ polyols were prepared with double metal cyanide catalysts                 HYDROXYL                                                                             UNSAT.                                                                             MOLE %                                                                              WT. %                                                                              FUNCTION-                                      POLYOL  NUMBER meq./g                                                                             MONOL MONOL                                                                              ALITY                                          __________________________________________________________________________    DIOLS                                                                         POLY-G 20-56                                                                          56.8   0.028                                                                              5.4   2.79 1.95                                           POLY-L 220-56                                                                         58.1   0.018                                                                              3.4   1.75 1.97                                           POLY-L 225-48                                                                         53.4   0.017                                                                              3.5   1.81 1.96                                           POLY-G 20-28                                                                          26.6   0.097                                                                              34.1  20.7 1.66                                           POLY-L 20-28                                                                          26.6   0.015                                                                              6.1   3.1  1.94                                           POLY-L 220-14                                                                         14.4   0.018                                                                              13.2  7.2  1.87                                           TRIOLS                                                                        POLY-G 83-26                                                                          25.5   0.092                                                                              43.1  20.9 2.12                                           POLY-L 383-26                                                                         27.1   0.018                                                                              10.4  3.8  2.77                                           POLY-G 85-28                                                                          26.8   0.095                                                                              40.4  19.1 2.13                                           POLY-L 385-17                                                                         17.4   0.017                                                                              14.6  5.6  2.68                                           POLY-L 330-18                                                                         17.8   0.018                                                                              15.1  5.8  2.67                                           __________________________________________________________________________

Hand cast elastomers were prepared from toluene diisocyanate (TDI)prepolymers (6% free NCO) extended with 4,4'-methylenebis(2-chloroaniline) (MOCA). A comparison of the physicalproperties ofthe elastomers prepared with the conventional 6000 molecular weighttriols to the elastomer prepared with the 6000 molecular weight triolcontaining a low unsaturation level (Table 2) showed that the lowermonol levels resulted in increased tensile strength (2300 vs. 1900 psi). A cast elastomer prepared with a 10,000 molecular weight triol showedeven more improvement in tensile strength (2700 vs. 1900 psi), a higherhardness value, and improved elongation.

                  TABLE 2                                                         ______________________________________                                        Physical Properties of Cast Elastomers                                        TDI Prepolymers (6% NCO) Extended with MOCA                                   INDEX 103, CURED AT 110 C.                                                                 P.P.    SHORE    TENSILE ELONG.                                  POLYOL       VISC    A        STR. psi                                                                              %                                       ______________________________________                                        POLY-G 85-28     3900    90     1910    290                                   POLY-G 83-26     3520    90     1900    300                                   POLY-L X-383-26  4000    90     2310    260                                   POLY-L X-330-18  6850    92     2730    390                                   ______________________________________                                    

EXAMPLE 2

TDI prepolymers (6% free NCO) prepared with 4200 molecular weight diolswere also extended with MOCA to make cast elastomers (Table 3). In thiscase the effect of the lower monol levels was clearly demonstrated bythe fact that the elastomer prepared with the new low unsaturation levelpolyol had a higher hardness value, significantly higher tensilestrength (2400 vs. 1600) and higher tear strength.

                                      TABLE 3                                     __________________________________________________________________________    Physical Properties of Hand Cast Elastomers TDI/DIOL Prepolymers (6%          NCO)                                                                          EXTENDED WITH MOCA, 103 INDEX, CURED AT 110 C.                                POLYOL     UNSAT. meq/g.                                                                          SHORE A                                                                             TENSILE STR. psi                                                                        ELONG. %                                                                             TEAR DIE C                         __________________________________________________________________________    POLY-G                                                                             20-28 0.097    87    1590      640    475                                POLY-L                                                                             X-220-28                                                                            0.015    93    2420      530    590                                __________________________________________________________________________

EXAMPLE 3

Softer elastomers were prepared from 2.5% NCO TDI prepolymers made with4200 molecular weight diols extended with MOCA (see Table 4). Once againthe low unsaturation level POLY-L polyol produced an elastomer withhigher hardness (75 vs. 63 Shore A), higher tensile strength (1180 vs.890 psi) and a higher tear strength (280 vs. 210 psi).

                                      TABLE 4                                     __________________________________________________________________________    Soft Elastomers - 2.5% NCO TDI Prepolymers -Extended With MOCA, 103           INDEX, CURED AT 110 C.                                                                SHORE A                                                                             TENSILE STR. PSI                                                                         ELONG. %                                                                             DIE C TEAR                                    __________________________________________________________________________    POLY-G 20-28                                                                          63     890       900    210                                           POLY-L 220-28                                                                         75    1180       600    280                                           __________________________________________________________________________

EXAMPLE 4

Soft elastomers were also prepared from 6% NCO TDI prepolymes extendedwith UNILINK™ 4200, a substituted aromatic diamine product of UOP, Inc.A comparison of an elastomer prepared with a conventional 6000 molecularweight triol to an elastomer prepared with a low unsaturation level 8000molecular weight triol (Table 5) showed higher hardness value and highertensile strength value in the elastomer prepared with the lowunsaturation level polyol.

                                      TABLE 5                                     __________________________________________________________________________    PHYSICAL PROPERTIES OF CAST ELASTOMERS                                        6% NCO TDI PREPOLYMERS EXTENDED WITH UNILINK 4200                             POLYOL  EXTENDER                                                                              SHORE A                                                                             TENSILE STR. PSI                                                                         ELONG. %                                     __________________________________________________________________________    POLY-G 85-28                                                                          UNILINK 4200                                                                          35    500        550                                          POLY-L 85-21                                                                          UNILINK 4200                                                                          40    875        500                                          __________________________________________________________________________

EXAMPLE 5

Cast elastomers were prepared with diphenyl methane diisocyanate (MDI)prepolymers made with 6000 and 10,000 molecular weight triols andextended with butane diol (Table 6). Both the low unsaturation 6000 mwtriol and the 10,000 triol produced elastomers with higher tensilestrength than the conventional 6000 mw triol.

                  TABLE 6                                                         ______________________________________                                        PHYSICAL PROPERTIES OF MDI CAST ELASTOMERS                                    9% NCO PREPOLYMERS EXTENDED                                                   WITH BUTANE DIOL                                                              TRIOL       SHORE A     TENSILE   ELONG.                                      ______________________________________                                        POLY-G 83-26                                                                              90          2150      340                                         POLY-L 383-26                                                                             90          2310      260                                         POLY-L 330-18                                                                             88          2370      450                                         ______________________________________                                    

EXAMPLE 6

MDI based cast elastomers were prepared with a conventional 4200 mwdiol, a low unsaturation level 4200 mw diol, and a low unsaturationlevel 8000 mw diol (Table 7). The diols were used to prepare 9% NCO MDIprepolymers and the prepolymers were extended with a 70/30 blend ofbutane diol/ISONOL 100 which is an N,N-bis(2-hydroxypropyl)-anilineproduct of Dow Chemical Corp. The elastomer prepared with the lowunsaturation level 4000 mw diol had significantly higher tensilestrength (2250 vs 570 psi), elongation (740 vs 210%), and tear strength(340 vs 120 psi) than the elastomer prepared with the conventional 4200mw diol. The elastomer prepared with the 8000 mw low unsaturation leveldiol also had superior properties to the conventional 4200 mw diolthough lower than the low unsaturation level 4200 mw diol.

                                      TABLE 7                                     __________________________________________________________________________    PHYSICAL PROPERTIES OF CAST ELASTOMERS                                        9% NCO MCI PREPOLYMERS EXTENDED WITH BDO/I100 70/30                           POLYOL  SHORE A                                                                             TENSILE STR. PSI                                                                         ELONG. %                                                                             DIE C TEAR                                    __________________________________________________________________________    POLY-G 20-28                                                                          85     570       210    120                                           POLY-L 220-28                                                                         83    2250       740    340                                           POLY-L 220-14                                                                         85    1590       650    280                                           __________________________________________________________________________

EXAMPLE 7

MDI prepolymers were prepared with a low unsaturation level 2000molecular weight diol and a conventional 2000 mw diol. The prepolymerswere extended with butane diol and cured at 110° C. both with andwithout catalyst. In both cases the elastomers prepared with the lowunsaturation level 2000 molecular weight diol had higher tensilestrength and higher tear strength although the difference was lessdramatic than with the higher molecular weight diols and triols. Withthe lower molecular weight diols there is a smaller difference in thefunctionality and unsaturation level values between the KOH and thedouble metal cyanide catalyzed polyol (see Table 8).

                                      TABLE 8                                     __________________________________________________________________________    PHYSICAL PROPERTIES OF CAST ELASTOMERS                                        9% NCO MCI PREPOLYMERS EXTENDED WITH BDO                                      DIOL    SHORE A                                                                             TENSILE STR.                                                                             ELONG. %                                                                             DIE C TEAR                                    __________________________________________________________________________    NO CATALYST, CURED 110 C., 16 H                                               POLY-G 20-56                                                                          89    2970       660    500                                           POLY-L 220-56                                                                         89    3180       650    560                                           COCURE 44 CATALYST, CURED 110 C., 16 H                                        POLY-G 20-56                                                                          90    2700       625    490                                           POLY-L 220-56                                                                         90    2750       550    590                                           __________________________________________________________________________

What is claimed is:
 1. A thermoset polyurethane or polyurea elastomermade by reacting an isocyanate-terminated prepolymer with achain-extender other than ethylene glycol, the isocyanate-terminatedprepolymer being the reaction product of a polyisocyanate and apolyether polyol prepared utilizing a double metal cyanide complexcatalyst and having a molecular weight of between about 400 and about15,000, said polyol having an end group unsaturation level of no greaterthan 0.04 milliequivalents per gram of polyol, the equivalent ratio ofNCO groups on said polyisocyanate to active hydrogen groups on saidpolyol plus chain extender being between about 1:0.7 and about 1:1.3,and the molar ratio of chain extender to polyol being between about0.15:1 and about 1.3:1.
 2. The elastomer of claim 1 wherein said chainextender is selected from the group consisting of diols, triols anddiamines, and combinations thereof.
 3. The elastomer of claim 1 whereinsaid chain extender is selected from the group consisting of4,4'-methylene bis(2-chloroaniline) ("MOCA"), butane diol, hexane diol,propylene glycol, bisphenol A, polyalkylene oxide polyols with molecularweights between 100-500, glycerine, trimethylol propane, propoxylatedadducts of glycerine or trimethylol propane diethyltoluene diamine,ethylene diamine, triisopropyl amine, N,N-bis(2-hydroxypropyl)-aniline,and combinations thereof.
 4. The elastomer of claim 1 which additionallycontains at least one compounding ingredient.
 5. The elastomer of claim4 wherein said compounding ingredient is selected from the groupconsisting of plasticizers, uv stabilizers, adhesion promoters, fillersand pigments.
 6. The elastomer of claim 4 wherein said compoundingingredient is employed in an amount of between 0 and about 75 weightpercent based upon the total weight of the composition.
 7. A thermosetpolyurethane or polyurea elastomer made by reacting in a "one-shot"process a polyether polyol, a polyisocyanate, and a chain-extender otherthan ethylene glycol, the polyether polyol being prepared utilizing adouble metal cyanide complex catalyst and having a molecular weight ofbetween about 400 and about 15,000, said polyol having an end groupunsaturation level of no greater than 0.04 milliequivalents per gram ofpolyol, the equivalent ratio of NCO groups on said polyisocyanate toactive hydrogen groups on said polyol plus chain extender being betweenabout 1:0.7 and about 1:1.3, and the molar ratio of chain extender topolyol being between about 0.15:1 and about 1.3:1.
 8. The elastomer ofclaim 7 wherein said chain extender is selected from the groupconsisting of diols, triols and diamines, and combinations thereof. 9.The elastomer of claim 7 wherein said chain extender is selected fromthe group consisting of 4,4'-methylene bis(2-chloroaniline) ("MOCA"),butane diol, hexane diol, propylene glycol, bisphenol A, polyalkyleneoxide polyols with molecular weights between 100-500, glycerine.trimethylol propane, propoxylated adducts of glycerine or trimethylolpropane diethyltoluene diamine, ethylene diamine, triisopropyl amine,N,N-bis(2-hydroxypropyl)-aniline, and combinations thereof.
 10. Theelastomer of claim 7 which additionally contains at least onecompounding ingredient.
 11. The elastomer of claim 10 wherein saidcompounding ingredient is selected from the group consisting ofplasticizers, uv stabilizers, adhesion promoters, fillers and pigments.12. The elastomer of claim 10 wherein said compounding ingredient isemployed in an amount of between 0 and about 75 weight percent basedupon the total weight of the composition.
 13. A method of fabricating acast elastomer which comprises the steps of:(a) fabricating a polyolhaving a molecular weight of between about 400 and about 15,000 andhaving a level of end group unsaturation of no greater than 0.04milliequivalents per gram of polyol, said polyol being fabricated in thepresence of a double metal cyanide catalyst, (b) reacting said polyolwith a polyisocyanate to produce an isocyanate-terminated prepolymer,and (c) reacting said isocyanate-terminated prepolymer with a chainextender other than ethylene glycol in a mold in order to produce a castelastomer.
 14. The method of claim 13 wherein said chain extender isselected from the group consisting of diols, triols and diamines, andcombinations thereof.
 15. The method of claim 13 wherein said chainextender is selected from the group consisting of 4,4'-methylenebis(2-chloroaniline) ("MOCA"), butane diol, hexane diol, propyleneglycol, bisphenol A, polyalkylene oxide polyols with molecular weightsbetween 100-500, glycerine, trimethylol propane, propoxylated adducts ofglycerine or trimethylol propane diethyltoluene diamine, ethylenediamine, triisopropyl amine, N,N-bis(2-hydroxypropyl)-aniline, andcombinations thereof.
 16. The method of claim 13 which additionallycontains at least one compounding ingredient.
 17. The method of claim 16wherein said compounding ingredient is selected from the groupconsisting of plasticizers, uv stabilizers, adhesion promoters, fillersand pigments.
 18. The method of claim 16 wherein said compoundingingredient is employed in an amount of between 0 and about 75 weightpercent based upon the total weight of the composition.
 19. A thermosetpolyurethane or polyurea elastomer made by reacting anisocyanate-terminated prepolymer with an ethylene glycol chain extender,the isocyanate-terminated prepolymer being the reaction product of anMDI polyisocyanate and a polyether polyol prepared utilizing a doublemetal cyanide complex catalyst and having a molecular weight of betweenabout 400 and about 15,000, said polyol having an end group unsaturationlevel of no greater than 0.04 milliequivalents per gram of polyol, theequivalent ratio of NCO groups on said polyisocyanate to active hydrogengroups on said polyol plus chain extender being between about 1:0.7 andabout 1:1.3, and the molar ratio of chain extender to polyol beingbetween about 0.15:1 and about 1.3:1.
 20. A thermoset polyurethane orpolyurea elastomer made by reacting in a "one-shot" process a polyetherpolyol, an MDI polyisocyanate, and an ethylene glycol chain extender,the polyether polyol being prepared utilizing a double metal cyanidecomplex catalyst and having a molecular weight of between about 400 andabout 15,000, said polyol having an end group unsaturation level of nogreater than 0.04 milliequivalents per gram of polyol, the equivalentratio of NCO groups on said polyisocyanate to active hydrogen groups onsaid polyol plus chain extender being between about 1:0.7 and about1:1.3, and the molar ratio of chain extender to polyol being betweenabout 0.15:1 and about 1.3:1.